1. Field of the Invention
The present invention relates to a tire detection instrument and more specifically, to an electronic measuring device for measuring the pressure and tread depot of a vehicle tire.
2. Description of the Related Art
For a safety driving of a car, it is important to maintain the tires of the car properly. Proper inflation pressure and sufficient tread depth are important factors in tire care. Except complicated inspection items, a car owner can measure the inflation pressure and tread depth of the tires by oneself.
Various measure devices are commercially available for measuring the inflation pressure and tread depth of vehicle tires. FIGS. 1 and 2 show a tire pressure and tread depth measuring instrument according to the prior art. According to this design, the instrument 1 comprises a meter 2, a connector 3, and a scale 4. The meter 2 has a pointer 2a coupled to a gear wheel 2b. The scale 4 has a rack 4a longitudinally disposed at one lateral side and meshed with the gear wheel 2b. When in use, the connector 3 is attached to the air valve of the tire (not shown) so that the inflation pressure of the tire is readable through the indication of the pointer 2a. At this time, the scale 4 is extended to the outside of the instrument 1 so that the user can attach the free end 4b of the scale 4 to the bottom edge of the tread pattern of the tire and the reference edge 2c of the meter 2 stopped against the outer surface of the tire and then read the reading 4c of the scale 4. The reading 4c indicated at this time is the value of the tread depth of the tire. This measuring instrument 1 has a simple structure. However, it is not convenient to use. When in use, the user must measure the inflation pressure of tire at first to have the scale 4 be extended out of the instrument, and then start measuring the tread depth of the tire. Further, because this instrument is a design of mechanical transmission, the value measured is not very accurate.